dvgrn wrote:Just posted a p556 2-engine Cordership gun on Entity Valkyrie's thread. All the signals from the left-side shotgun come from one signal loop, in an unusual way involving quadri-Snarks, CP semi-Snarks (color-preserving) and CP-semi-cenarks.

Okay, here's a cleaner version of the p556 gun. This time it can be easily packed into a smaller space without getting into too many retiming difficulties. Someone else is welcome to do that -- I'm not going anywhere near it again until at least next weekend.

The whole right side is just a temporary placeholder thrown together in five minutes. It could be replaced by south-traveling Herschels feeding BNE edge shooters, possibly fed by another quad-signal loop (or even the same one?)

EDIT: Repaired the labels to match the different phase of the quad-signal loop.

dvgrn wrote:The whole right side is just a temporary placeholder thrown together in five minutes. It could be replaced by south-traveling Herschels feeding BNE edge shooters, possibly fed by another quad-signal loop (or even the same one?)

Or, more simply, each of those pairs of guns producing 78-tick-separated G0 pairs can be replaced with a single gun containing two 78-tick-separated Herschels in the same loop:

I don't know whether it's worth trying to coax both glider streams from the same gun. Probably, I'd imagine. And then you could get the fifth SW-bound glider from attaching a semi-snark to a third output.

What do you do with ill crystallographers? Take them to the mono-clinic!

calcyman wrote:I don't know whether it's worth trying to coax both glider streams from the same gun. Probably, I'd imagine. And then you could get the fifth SW-bound glider from attaching a semi-snark to a third output.

True enough. I knew that side was a lot easier, so I didn't worry about it -- but I didn't realize quite how easy!

Getting both glider-pair streams from the same gun is just a matter of looking up an H-to-2G splitter in the glider adjustment toolkit with a Oe2/Eo2 rating. NW31 is perfectly serviceable, for example, though there may be others with better geometry:

The fifth (circled) glider might actually be compatible with the extra output of the gun, I'm not sure. It would take some rework to use the edge-shooter side of the NW31 to put a stream near that fifth-glider stream. Otherwise you need a syringe and edge-shooter anyway, not just a (semi-)Snark chain.

Below is the current stamp collection of semi-Snark/cenark mechanisms and their ratings. I had the sign wrong for some of them in a previous posting. The toolkit needs an appropriate G->4G and two period doublers to get to universal adjustabililty, as shown here. With only one doubler it's kind of the luck of the draw whether the timing can be made to work out.

#C A period 96 Cordership with an edge near the front which can be used#C to turn sideways gliders into forward gliders. This uses a two-engine#C block and boat puffer which is cleaned up by a two-engine Cordership.#C This is an improvement of a previous version of this reaction.#C David I. Bell, 9 January 2018x = 51, y = 8823bo$22bobo$21booboo$22bobbo$24b3o$24bobo$25boo$25boo12boo$39boo3$5bo17bo$24bo$bo7bo14boo$bo8bobb3o7b3o$o4boo3bobb3o31boo$bobo6bobboobbo29boo$boboo10bobo6b3o$15b3o4bo4bo$6bo15boo3bo14boo$24b4o14boo$43boo$38bob4o$37bobboo3$34bo3bo$34bobbo$33bo3bo10b3o$33booboo$9bo23boobbo$8bobbo22b3o$16bobboo14bo$12bo4boobo$6bo5bo8bo$7bo11boo$11bo11bobo$9boo$23bobo3$23b3o$23b3o$24bo$25boo$26bo18boo$25bo14boo3boo$40boo4boo$45boo$45boo$23boo20bo$23boo$24bo$8bo31bo$8bo5b3o24boo5boo$7bobo3boobbo21bobo6boo$8bo3bo5bo5bo14bo$8bo3bo10bobbo13boo$13bobboo6boo16bo$14boo24b3o$39boboo$41boo$38bo$38bo$36boo$36bobo$35b3o$35bo$21bo14boo$11boo9boo12boo$10bob3o8boo$10bo3bo10bo$11boobo5b5o6boo$12bo10bo6bobbo$29booboo$28bobo$27boo$27bo3bo$28bobbo$15boo11b3o$15boo$27bo$27bo$24boo$24boo$24bobbo$25b3o$26bo!

The only downside of this improvement is that the lanes near the forward glider are obstructed, preventing the creation of close salvos using multiple of these reactions. But then, we do have the other reactions in that case.

Meant to mention -- this could (probably) be trivially reduced at least to 13 still lifes, if there is some two-object constellation that produces a switch engine in a different orientation -- i.e., when a trigger glider hits it from behind.

Are there any such constellations known, or has it been proven that there aren't any such?

Unfortunately it looks like any seeds where the switch engine travel directly away from the trigger glider, must be made of fairly rare still lifes, or possibly less common oscillators like beacons or toads. (Or there will be hundreds of 3-still-life constellations that would work, but that wouldn't save anything.)

I fixed up my enumerator script a little, so now it handles blocks, tubs, boats, beehives, ships, loaves, eaters, longboats, ponds, and blinkers. It found about a quarter of a million two-object constellations that fit inside a 16x16 box.

Ten of those constellations produced a clean switch engine, but with my enumerator half the results are always mirror images of the other half. So there were really only five cases, including chris_c's original two-boat one:

Still seems like there should be a way to reduce the number of still lifes somehow. Maybe there's a better cleanup constellation, or possibly there's a 2sL splitter that delays one of its outputs long enough that it could be connected directly to one of the forward signals, thus saving one turner object.

It is nice due to the p8 sparks. Maybe someone finds a way to attach the tail to a shorter spaceship front.Moreover, it is listed that for (4,0)c/8 there is no asymmetric spaceship with width 10 or smaller. But we have a known example with width 11:

2718281828 wrote:I did some computations using zfind for (4,0)c/8. The results for a gutter spaceship with width 17 were negative. But for a width of 19 I got a couple positive results:This is an example:

It is nice due to the p8 sparks. Maybe someone finds a way to attach the tail to a shorter spaceship front.

This p8 tagalong was first found by Paul Tooke on 4 Feb. 2002, and can be seen in the Life Lexicon under "still life tagalong". Also, zfind can only prove the nonexistence of ships of type (n,0)/p where gcd(n,p)=1. Therefore it is not capable of proving the minimum width for (4,0)c/8 or (6,0)c/12 ships.

2718281828 wrote:it is listed that for (4,0)c/8 there is no asymmetric spaceship with width 10 or smaller. But we have a known example with width 11:

This ship actually has a width of 14. The width of an orthogonal spaceship is typically considered to be the width of the reaction envelope after the ship has been run through one full period (i.e., the width of the pattern after it has been run in LifeHistory). For example, the LWSS has a width of 5, even though each phase only has a width of 4.

I'm under the impression that programs called -find are just much better at finding ships than programs called -search. Is that true? If so then there's not much point looking for a knightship with LLS.

Macbi wrote:I'm under the impression that programs called -find are just much better at finding ships than programs called -search. Is that true?

This is not true. For example, WLS and JLS are much faster than gfind and even zfind when doing a diagonally-shaped search. I'm not really sure why this is. WLS and JLS also allow for greater customization of the spaceship shape. By the way, knight2 is faster than gfind for p6 and p7 knightship searches.

A for awesome wrote:If I remember right, the existence of p6 knightships with width <= 15 has already been ruled out.

This is recorded on the spaceship search status page. In this case, the "width" is in the dimension of least travel. This can be seen in Tim Coe's width-15 partial p6 knightship:

That's interesting. So LLS is potentially a useful tool for finding a knightship. On the other hand I just ran searches in LLS with -b8, -b9, -b10 and -b11 and they took 2s, 20s, 200s and 2000s. So unless calcyman's new distributed search is much faster than glucose-syrup, we're not going to get anywhere near width 15.

I notice that knight2 can't run a search with translation 2 in the y direction. Is there some other program that could be used to bound the height of a knightship?

EDIT: Also, can gfind and co. be used to find oscillators? What are the known bounds on a p19?

You are almost certainly not going to find a p19 with any of these direct search methods. Even period-9 is pushing the limits of what these programs can search for.

That's all true enough, but the "known bounds" question is still an interesting one -- maybe particularly for LLS.

We can certainly say that we know that no p19 exists that fits inside an MxN bounding box in all phases, for various small M and N. It would be interesting to run searches for different (period, M, N) combinations, increasing M and N for each period until we stop getting quick negative results -- and just see where that dividing line might be for each period.

Using ideas like those in LLS (but my own code), using the SAT solver glucose, I was able toget a "partial" (if having six cells wrong can be considered a partial) (1,2)c/6 knightship inCGOL to this point: